In Use - Mystery Glitches

DVDs are recorded in a high quality MPEG2 digital video format. Unfortunately the best available video connection on the DX2 is an analogue S-video port. S-video is better than a standard composite connection (which is also analogue) because it is capable of transferring a video's brightness information separately from its colour information. This allows S-video to transfer a higher-bandwidth signal from the original video to your monitor than a standard composite connection, which combines the colour and brightness signals.

But even though S-video is capable of an improved picture, it remains an analogue signal. Since DVDs are digital, the content must be converted to analogue as it passes through the S-video connection. Every time you transfer a video from one format to another the "generation" causes a loss in the integrity of the resulting copy. Small details can be lost with each conversion and, therefore, each new generation looks slightly worse than the last. It's not unlike a photocopy. The first photocopy of an original might look pretty good, but if you keep making copies from copies, the flaws soon become obvious and distracting.

If I count a "generation" as an analogue-to-digital, digital-to-analogue or digital-to-digital transcoding conversion, the output of the DX2 is a second or third-generation copy from the DVD original (Gen 1: DVD to analogue output; Gen2: DX2 A/D conversion; Gen 3: (Optional) DX2 digital transcoding to final output format).

A small snag in the capture process with the DX2 is that the video will occasionally become very pixilated for a few frames and then revert back to normal. The pixilation is not extremely noticeable, especially when viewing the video on a low resolution standard definition television; however, it can get a bit annoying on a higher resolution display.

Figures 7 and 8 illustrate the problem during a DVD capture. The source was a standalone DVD player using the S-video connection being recorded directly to a recordable DVD. However, the phenomenon does not seem to be limited to direct-to-DVD recordings or any specific compression format. I kept an eye on CPU usage while capturing video in all of the available file formats and recording sources and it did not exceed an average of 45%. So over-taxing the CPU (Table 1) does not seem to be the cause of the pixilation.

Figure 7: Example of image pixelation glitch (click to enlarge)

Figure 8: A few frames later, the image becomes clear again (click image to enlarge)

Table 1: Test Computer

Motherboard

MSI Platinum K8N Neo 4

CPU

AMD Athlon 64 3800+

Memory

2X 512 Corsair PC3200 (1024MB)

Video Card

Geforce 7900 GTX

I also noticed that the audio sounds a little shaky while the capture is running. It turned out that the audio shakiness is normal (according to ADS Tech) and won't affect the final product.